Vulcans have a nictitating membrane, or "inner eyelid", that protects them against the harshness of 40 Eridani. (TOS: "Operation: Annihilate!")

Internally, Vulcan blood is copper-based, and is dark green in color. Their heart is where a Human's liver is, and their brains have a noticeable layered structure. Their blood types include T-negative, which is extremely rare. (TOS: "Journey to Babel") One of the more common types is S-indifferent. (Orion Press: "The Choice")

Historically, male Vulcan names start with the letter "S" to honor Surak, the father of Vulcan logic, and female Vulcan names begin with "T" to honor T'Plana-Hath), the matron of Vulcan philosophy.

Vulcan males, at least, undergo a trial by ordeal, the kahs-wan, at age 7. If completed successfully, they are considered adults in Vulcan society. (TAS: "Yesteryear", Orion Press: "Contempt of Council")

After centuries of bloody wars and untold violence on the Vulcan homeworld, roughly around the 4th century on Earth, the Vulcan embraced the teachings of Surak. Since then, the Vulcans have tried to be logical beings, attempting to hide their emotional and passionate core behind a facade of non-expression.

The date of the Surakian revolution differs according to continuity. As well, in many continuities, the revolution was also the impetus -- for those who would one day call themselves Romulans -- to leave Vulcan. (TOS novel: The Romulan Way, TOS novel: Spock's World)

By the mid-22nd century, Vulcans had lost the original meaning of Surak and began to revert to their original state, engaging in territorial disputes and minor wars with Andoria, until Syran and Jonathan Archer was able to recover the Kir'Shara, the body of the original writings of Surak. (ENT: "Kir'Shara")